Not even that! As Poland showed, they barely even made an impact! People will just stop fucking and probably have even less babies as a result. If it was allowed you'd have someone "Oh well, worst case scenario abortion exists" and then potentially go, with their own choice, "Maybe kids ain't that bad after all".
Communist Romania tried that as well, and as you also pointed out, they had a lot of orphans. Like, orphanages were full of kiddos. And they also couldn't emigrate to where abortion is legal ofc, like they can in Poland and US states where it's banned, increasing depopulation.
Here's what the christchuds are gonna get, though. They're gonna have a bunch of sheeple they can manipulate more easily. It's no secret that dysfunctional family ppl end up engaged in some questionable ideologies. But that also means they can become commies that are absolutely against anything remotely Christian...or maybe those who realize that they can impose Christianity with communism, where economic 5 year plans come from God himself. And fun fact; Francoist Spain is where many worker co-ops started thriving and are relevant even today!
Christianity and socialism are a better fit than Christianity and free market capitalism. If you gave an alt right Amerimuttistan first /pol/ tard ,who jerks off to Dennis Prager, economic policies of Axis countries without naming them, they'd say these are socialist or even communist policies!